The present invention relates to a charged particle beam device.
Charged particle beam devices are used in order to observe minute structures. During a semiconductor manufacturing process, charged particle beam devices that employ charged particle beams such as electron beams to measure or inspect the dimensions or the shapes of semiconductor devices are used. One example is a scanning electron microscope (SEM). An SEM radiates an electron beam (hereinafter, primary beam) generated from an electron source to a sample to be observed, and secondary electrons generated as a result are detected by a detector and converted to an electrical signal, thereby generating an image.
In order to detect secondary electrons, it is necessary to separate the trajectory of the secondary electrons (hereinafter, secondary beam) from the primary beam. Patent Document 1, for example, discloses a magnetic sector as an optical device to perform such separation. The magnetic sector consists of two magnetic plates with coils embedded for exciting a magnetic field. The primary beam and secondary beam are deflected in different directions by the magnetic field in the magnetic sector and thus separated.
When shifting the field of view, it is effective to deflect the primary beam by a deflector using an electric field or a magnetic field, thereby shifting (hereinafter referred to as image shift) the irradiation position on the sample. The irradiation position on the sample affects the secondary beam. Patent Document 2 discloses an E×B filter that generates an electric field and a magnetic field that deflect only the secondary beam and not the primary beam. In Patent Document 2, the secondary beam is controlled such that during an image shift, the E×B causes the change in trajectory of the secondary beam to be corrected.
Patent document 1: U.S. Pat. No. 5,319,207
Patent document 2: US 2015/0357153